A history of the early days of Royal Navy destroyers, and how they evolved to meet new military threats.   In the late nineteenth century the advent of the modern torpedo woke the Royal Navy to a potent threat to its domination, not seriously challenged since Trafalgar. For the first time a relatively cheap weapon had the potential to sink the largest, and costliest, exponents of sea power.   Not surprisingly, Britain's traditional rivals invested heavily in the new technology that promised to overthrow the naval status quo. The Royal Navy was also quick to adopt the new weapon, but the British concentrated on developing counters to the essentially offensive tactics associated with torpedo-carrying small craft. From these efforts came torpedo catchers, torpedo-gunboats and eventually the torpedo-boat destroyer, a type so successful that it eclipsed and then usurped the torpedo-boat itself. With its title shortened to destroyer, the type evolved rapidly and was soon in service in many navies, but in none was the evolution as rapid or as radical as in the Royal Navy.   This book is the first detailed study of their early days, combining technical history with an appreciation of the changing role of destroyers and the tactics of their deployment. Like all of Norman Friedman's books, it reveals the rationale and not just the process of important technological developments.